1. Field of the Invention
The present invention relates to a contour measuring apparatus.
2. Related Background Art
In the contour measurement of an object, for example, a tooth, the following apparatus are used: (a) a three-dimensional measuring apparatus by a contact type probe, (b) a measuring apparatus by a micrometer, (c) a measuring apparatus by an interference fringe of a light, (d) a measuring apparatus by image processing of camera photographing, and (e) a 5-plane measuring apparatus by a laser.
In the apparatus (a), an apparatus which measures five planes instead of one plane is available, but because it is of contact type, it is necessary to finely sample the object in order to measure it with a high precision, and hence it takes a long time for measurement (approximately 10 hours).
FIG. 1 illustrates a principle of the 5-plane measurement. In FIG. 1, numeral 1 denotes a tooth. FIGS. 2A and 2B illustrate the 3-dimensional measurement by a 3-dimensional measuring apparatus having a contact type probe. In FIG. 2A, numeral 2 denotes a contact type probe. In FIG. 2B, numeral 3 denotes grid-like measurement points. Of the grid-like measurement points 3, the points outside the tooth 1 are not measured.
In the apparatus (b), an object or the tooth 1 is mounted on a position changing table 4 and it is measured by applying a needle 5 of a micrometer to the measurement points while the table 4 is driven step by step. Accordingly, the precision of the measurement is low and the measurement time is long. FIG. 3 illustrates the measurement by a micrometer.
In the apparatus (c), the measurement precision around the contour of the object or the tooth 1 is low as shown in FIG. 4. In FIG. 4, numeral 6 denotes an interference fringe.
In the apparatus (d), the precision is low due to the manual measurement as shown in FIG. 5. As shown, a person must trace an outline 9 of an image 8 of the tooth 1 displayed on a display screen 7, by a pen 10.
In the apparatus (e), the apparatus is of large scale because of the necessity to measure five planes and the apparatus is expensive.